We are evaluating the performance of a PCR assay designed in our laboratory for the diagnosis of Clostridium difficile disease. Our assay uses a primer set to detect the toxin A gene and another set to detect the toxin B gene. Endpoint detection of PCR products is an ELISA format. Our PCR assay will be compared to the following methods for diagnosis of C. difficile disease: toxigenic culture, cytotoxin assay, an ELISA for detection of toxins A and B, and a commercial PCR assay that detects the presence of the genes for both toxins A and B. All assays except our PCR assay have been performed on 144 stool specimens. We discovered that a unique toxin A deficient strain of C. difficile was not detected by our PCR assay. We have redisigned our toxin A gene primers and detection probe to allow us to detect this strain and have revalidated our PCR assay for detection of the toxin A gene. Once our PCR assay has been performed on all 144 specimens a chart review will be performed for specimens with conflicting results. Our results will demonstrate if PCR is a useful tool for diagnosis of C. difficile gastrointestinal disease. Note: This project has been merged with another project(CL010325-03 DLM) entitled "Evaluation of a Commercial PCR assay for Diagnosis of C. difficile Colitis."